Improvement in balanced slide-valves



THOMAS H. HOLLIS.

Improvement in Balanced Slide Valves. N0. 123,260. `PatentedJan.30,1872.

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THOMAS H. HOLLIS, OF MOUNT VERNON, INDIANA, ASSIGNOR OF ONE-HALF HIS RIGHT TO ALVIN P. HOVEY, OF SAME PLAGE. l

IMPROVEMENT IN BALANCED SLIDEI'VALVES.

Specification forming part of Letters Patent No. 123,260, dated January 30, 1872.

I, THOMAS H. HoLLIs, of Mount Vernon,

Posey county, Indiana, have invented a new imand usei'ul Balanced Slide-Valve, of which the following is a specification:

Vith the slide-valve as commonly used in high-pressnre steam-engines much power is wasted in overcoming the severe friction of the valve on its seat; and the object ot' my improvement is to remedy this defect by providin g means for a coun ter pressure underneath the valve.

Figure l is a longitudinal section ot1 avalve and seat embodying my invention, and Fig. 2 is a plan viewr ot the same.

My valve A has the customary central cavity a, which serves to connect the two ends of the cylinder successively with the exhaust. My valve has two longitudinal extensions, B B', Whose sliding faces are ush With the main or central portion. Between the central and external portions are passages C C for the live steam to the respective ends ofthe cylinder alternately. D is an air-pump, Whose piston-rod d may be Worked With varying speed, as required, by suitable connection with the engine. This pump operates to propel airinto passages E, which terminate under the valve extensions B B so as to oppose to the downward stress ofthe steam a counteractin g pressure of compressed air, and thus to relieve the valve ot' the friction otherwise incident to its use. The compressed-air passages E may, at their disohargingends, take the form of chambers e, so as to give a greater etl'ective area of counter pressure, or the faces ofthe extension B B maybe chambered for that purpose. The passages E may communicate with a reservoir, F, in order to preserve a uniform pressure.

Claims.

set my hand.

THOS. H. HOLLIS.

Vitne-sses:

Gao. H. KNIGHT, ALVIN P. Hovnr. 

